Author

Award Date

Degree Type

Degree Name

Department

Geoscience

First Committee Member

Pamela Burnley

Second Committee Member

Wanda Taylor

Third Committee Member

Michael Wells

Fourth Committee Member

Ashkan Salamat

Number of Pages

99

Abstract

Rheological studies of rocks and minerals allow researchers to study the grain-scale deformation mechanisms that govern large-scale geologic processes from mountain building to mantle mixing. Deforming rock samples with high pressure and temperature apparatuses similar to the Griggs piston cylinder apparatus allows us to simulate deformation at depth. However, many apparatuses are limited to “cook-and-look” analysis and require modeling techniques to determine the evolution of deformation patterns found in experimental samples. A previous study used two-dimensional finite element models to analyze the development of stress and strain patterns in polycrystalline rocks. The study suggested rhythmic patterns in deformed rocks develop as a result of stress percolating through the elastically and plastically disordered system. Furthermore, similar strain heterogeneities have been observed using 2D digital image correlation software that measures strain in experimentally deformed materials using computer algorithms that track incremental changes in optical images. This study used slabs of tiger’s-eye, a quartz aggregate made up of stacked columnar grains, to simplify the geometry of the material deforming in the Griggs apparatus. By modifying the traditional sample assembly from cylindrical to parallelepiped, I developed a method to use 2D digital image correlation for strain mapping of samples deformed at high pressure and track the microstructural changes within specific sets of grains before and after deformation with grain contrast imaging.